The present invention relates to new fermented dairy products flavoured by the incorporation of warm flavours.
The general name xe2x80x9cwarmxe2x80x9d flavours is used to designate flavours such as chocolate, caramel, vanilla, coffee, praline, nougat and/or the flavours of oleaginous fruits (walnut, hazelnut, almond, pistachio nut, cashew nut), and the like.
These aromas, which are generally in great demand from consumers, are widely used in the food industry for the manufacture of desserts. However, their use for flavouring fermented dairy products (for example of the type including yoghourt, milk drinks, fromage frais or derivatives thereof) is limited.
Although fermented dairy products (in particular of the yoghourt type) flavoured with warm flavours are proposed commercially, they are not appreciated by the majority of consumers because of the presence of an aftertaste which alters the true taste of the flavours used.
The inventors have now observed that this organoleptic incompatibility between warm flavours and fermented dairy products was essentially due to the acidity of the latter, which results from the production of lactic acid, causing a reduction of the pH, during fermentation.
Fermented diary products normally have a pH after fermentation of between 4 and 5 approximately, and a Dornic acidity greater than 80xc2x0 D, generally between 80 and 150xc2x0 D approximately, depending on their protein content.
The Dornic acidity reflects the buffering capacity of the dairy product during its fermentation; it is expressed in degrees Dornic (xc2x0 D): one degree Dornic corresponds to the quantity (in ml) of N/9 sodium hydroxide necessary to bring the pH of the product to pH=8.3, or alternatively the quantity of lactic acid (in mg) in 10 ml of product.
The inventors have discovered that if the Dornic acidity of a fermented dairy product was reduced while its pH was kept at a value less than or equal to 5, a preparation was obtained which could be flavoured with xe2x80x9cwarmxe2x80x9d flavours without denaturing them.
The subject of the present invention is a flavoured fermented dairy product characterized in that its Dornic acidity is 20 to 80 degrees Dornic, preferably 30 to 70xc2x0 D, and advantageously 40 to 60xc2x0 D, its pH is 4 to 5.5, preferably 4.5 to 4.9, and in that it is flavoured with a warm flavour.
Preferably, the said warm flavour is chosen from chocolate, caramel, vanilla, coffee, praline, nougat, walnut, hazelnut, almond, pistachio nut and cashew nut flavours and the like.
Although an acidity of up to 80xc2x0 D can sometimes be acceptable, for example in the case of certain products flavoured with chocolate, it is preferable in most cases, for an optimum preservation of the organoleptic qualities, especially when flavours such as coffee are used, that the acidity does not exceed 70xc2x0 D, and advantageously 60xc2x0 D.
Preferably, the flavoured fermented dairy products in accordance with the invention have a protein content (w/w) of 1 to 10%, and advantageously of 2 to 6.5%.
According to a preferred embodiment of a flavoured fermented dairy product in accordance with the present invention, it is a product of the yoghourt type or of the fromage frais type, characterized in that, for a protein content (w/w) of 2% to 10%, and a fat content (w/w) of less than or equal to 15% approximately, preferably of 3 to 12%, its pH is 4 to 5.5, and its Dornic acidity is 20 to 120xc2x0 D, preferably 40 to 70xc2x0 D.
According to another preferred embodiment of a flavoured fermented dairy product in accordance with the present invention, it is a product of the fermented drink type, characterized in that, for a protein content (w/w) of 1% to 5%, and a fat content (w/w) of less than or equal to 5% approximately, preferably of the order of 1.5%, its pH is 4 to 5 and its Dornic acidity is 20 to 70xc2x0 D, preferably 30 to 60xc2x0 D.
For the production of a fermented dairy product in accordance with the present invention, the fermentation of a dairy raw material is carried out by at least one microorganism capable of performing lactic acid fermentation; it represents in particular microorganisms normally used in lactic ferments, such as Lactobacillus sp., Lactococcus sp., as well as Bifidobacteriae sp., and in particular in yoghourt ferments; preferably, at least one lactic acid bacterium chosen from the group consisting of Lactobacillus bulgaricus and Streptococcus thermophilus will be used.
The dairy raw materials which can be used for carrying out the present invention are obtained by reducing the buffering capacity of milk, by demineralization and/or by reducing the content of proteins, in particular of calcium phosphocaseinate. The milk used may be derived from any mammalian species, or may be a mixture of milk from various species; it may be, as a whole or in part, milk reconstituted from powdered milk; it may optionally be partially or fully skimmed, supplemented or otherwise with vitamins, sugars or mineral salts.
The reduction in the protein and mineral salt concentration may be obtained by diluting the milk; the demineralization may be obtained by removing the mineral salts either solely from the soluble phase of the milk, or from the soluble phase and from the micellar phase.
To reduce the mineral salt concentration of the soluble phase of the milk, it is possible to carry out a diafiltration, especially on an ultrafiltration membrane, and/or a dilution. The dilution makes it possible, in addition, to also reduce the protein concentration.
The diafiltration of the milk can be carried out directly against water. It is also possible to concentrate the proteins beforehand by ultrafiltration on a membrane. Advantageously, the VCF (volume concentration factor) is 1.2 to 5; a retentate is thereby obtained which has a protein content of 3.8 to 18%.
This retentate is then subjected to diafiltration and/or to dilution.
The diafiltration rate (corresponding to the number of volumes of water added and to the number of volumes of permeate removed through the ultrafiltration membrane, relative to the volume of milk or of ultrafiltration retentate) is advantageously 0.5 to 5.
The dilution rate is advantageously less than or equal to 9, depending on the mineral salt and protein concentration desired for the product which will be subjected to fermentation.
To demineralize both the soluble phase and the micellar phase of the milk, the inventors have developed a process using partial demineralization of the milk under CO2 pressure, followed by a rise in the pH of the demineralized milk, by degassing.
The subject of the present invention is also this process which comprises at least:
a) the solubilization of CO2 under pressure (carbonation), in a milk (optionally diluted or concentrated beforehand), whose protein concentration is between about 25 and about 150 g/l, in order to reduce the pH of the said milk to a value of between 5 and 6.5, preferably between 5 and 5.8;
b) the partial removal, by diafiltration under CO2 pressure, of the soluble mineral salts (namely the minerals initially present in the soluble phase of the milk, and the mineral salts released from the micellar phase by the acidification), until a calcium quantity per gram of protein equal to 30% to 80%, preferably 40 to 70%, of the initial quantity is obtained;
c) the increase in the pH of the diafiltration retentate, by removal of the CO2 (decarbonation), until there is a return to a pH close to the pH of a non-carbonated milk having the same protein concentration as that of the said diafiltration retentate.
According to a preferred embodiment of the process in accordance with the present invention, the milk used is concentrated, until the desired protein concentration is obtained, either prior to the carbonation of step a), or during the diafiltration of step b).
According to another embodiment of the process in accordance with the invention, the decarbonation of step c) is carried out until there is a return to a pH at least equal to 6.2 and preferably greater than or equal to 6.4.
According to yet another embodiment of the process in accordance with the invention, steps a) and b) are carried out at a temperature of between 0 and 20xc2x0 C., and step c) at a temperature of about 20xc2x0 C. to 70xc2x0 C. and preferably between 20 and 40xc2x0 C.
The pH obtained at the end of step a) depends on the quantity of CO2 solubilized in the aqueous phase, which itself depends on the pressure used and on the temperature of solution.